Single finger-opening resilient safety closure caps are generally useful for arthritic sufferers needing quick and easy access into medication receptacles and the like. Most of these previously known closures include a finger depressible region for allowing a finger to press the closure, permitting the closure's removal from a container or receptacle. For example, U.S. Pat. Nos. 3,934,745 to Lovell; 4,187,953 to Turner; 4,220,262 to Uhlig et al; and 4,500,006 to Lafortune et al all disclose single finger opening collapsible closures for containers including finger depressible regions to convert the downward force executed by the finger into a disengagement force to remove the closure from the container. However, while these closures facilitate easy single finger removability, they are not "childproof", and therefore they allow children unauthorized access to a container's contents.
Rubber and other elastic bottle stoppers or plugs have been long known. The U.S. Pat. No. 3,578,193 to Steiner shows such an elastic stopper in the form of a single finger opening closure equipped with a finger receiving well, the closure being removed from a container when finger pressure is applied within the well. Also see Bramming, U.S. Pat. No. 2,746,632. Unfortunately, due to the closure's elasticity, changes in ambient temperatures may cause the premature opening of a container utilizing these types of closures. Additionally, elastic closures per se, typically used in conjunction with laboratory test tubes and the like, are relatively expensive to mass produce because of compounding requirements and the necessity of using relatively large quantities of material. Other disadvantages of elastic stoppers when employed in the pharmaceutical packaging industry include the fact that they are usually formed of compounded materials, components of which may cause contamination, or eventual degradation.
The U.S. Pat. No. 4,413,748 to Kessler et al discloses a double finger-collapsible closure equipped with a pair of spaced, D-shaped, finger receiving wells for permitting the removal thereof upon finger pinching motion as a one-piece molded structure, utilizing a resilient thermoplastic material, such as polyethylene or polypropylene, which does not readily deform or dis-shape when exposed to increased ambient temperatures. Furthermore, this cap is childproof as a child's attempt to deform or rotate a closure of this type would be very difficult, deterring further attempts of unauthorized access. However, this construction, because of having two finger wells, is often not suitable for smaller containers such as bottles. It is also sometimes difficult for arthritic sufferers to grasp and remove.
The U S. Pat. No. 4,691,839 to Ullman discloses a round two-well single finger-collapsible closure for permitting the removal thereof. The cap is removed by inserting a single finger within the finger receiving well, pressing the side wall thus contractably deforming a bar shaped portion and the sidewall of the second well, disengaging the cap and then lifting the cap upwardly. While being a useful device, it is more difficult and expensive to manufacture than the present invention. Further, the rectangular or square configuration of the cap according to the present invention and the opening which it closes provides a greater pour area at the edge of a round can in comparison to a round cap and opening on a can holding equivalent material. This square or rectangular pour area clearly results in a faster pour for equivalently contained material.
Containers for keeping potentially dangerous materials, such as medicines or toxic materials such as lye, must be provided with closures which are easy to install and remove, and which securely retain the solid materials within their containers. Closures must be operable with sufficient ease to assure that container contents are not inadvertently spilled or otherwise discharged during closure installation or removal.
It is desirable that closures for dangerous material containers be "childproof" in the sense that at least two distinct types of movements must be performed in proper sequence to effect closure removal. Furthermore, it is desirable that such closures have relatively simple configurations which can be molded easily from relatively inexpensive plastic materials. Additionally, in some instances there is a need to provide closures which will prevent pressure buildups by venting gases from within a container.
Except for Kessler U.S. Pat. Nos. 4,413,748 and Ullman 4,691,839, previously proposed container closure caps have not adequately addressed the foregoing needs. Many are either undesirably difficult to operate, or they close insecurely. Many are of unduly complex configuration, have unattractive appearances, and/or are undesirably expensive to mold from plastic materials. Most fail to address the need for a gas venting capability.
In comparison to the present invention, no single finger opening resilient cap has previously been available which will very simply prevent an unauthorized child's access, provide an easy removable closure for adults, especially adults afflicted with arthritis and at the same time reduce manufacturing costs and increase the pour rate of an equivalent material.